Is there a way to sterilize the entire volume (inside and out) of a solid object like a core of rock or concrete? I would like to kill any microbes that may be living inside these rock samples (i.e., endolithic microbes).
I have considered autoclaving, dry heat sterilization, microwaving, and gamma irradiation. I am assuming that methods like UV irradiation and flame sterilization will not work because they mainly sterilize surfaces. Also, I would like to use a method that minimizes changes to the rock substrate.
I have drilled out cylindrical cores of rock and concrete approximately 50 mm long and 40 mm in diameter. These weigh around 130 grams and have bulk densities around 2.4 g cm-3.
I am not sure where to start. Any advice would be appreciated. Thank you.
In general, I would like to measure the respiration of endolithic microbes as they are in their rock substrates, and I'd like some controls. I would like to incubate rock samples and measure changes in CO2/O2 concentrations in the incubation chambers over time. This is similar to what you'd do for a soil respiration assay, but a little less straightforward. It would be nice to compare "live" rocks to sterilized rocks to be more certain that gas changes are due to the microbes (and not any non-biological processes).
I will not have a way of determining if the sample was totally free of live microbes, but having rock cores in which most microbes have been killed or inactivated would help me narrow down how much the live microbes are doing by themselves.
Thanks for your interest! I hope that explanation makes sense.
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